High torque wind turbine blade, turbine, and associated systems and methods

ABSTRACT

A blade for a wind turbine can include an elongated and curved sheet having a root, a tip positioned opposite the root, a leading edge spanning between the root and the tip along a length of the blade, and a trailing edge spanning between the root and the tip opposite the leading edge. The blade can include a generally concave surface formed by curvature of the blade about a longitudinal axis. The blade can further include one or more air dams, which can be in the form of strip elements oriented transverse to the longitudinal axis and extending away from the concave surface. The air dams improve torque and efficiency of the blade. In some embodiments, an edge of the root can include a plurality of curved projections distributed thereon. A wind turbine system can include a generator and a wind turbine having a mounting element to support turbine blades.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 15/709,873, filed Sep. 20, 2017, which is acontinuation of U.S. patent application Ser. No. 15/462,686, filed Mar.17, 2017 and issued as U.S. Pat. No. 9,797,370, all of which areincorporated herein in their entirety by reference.

TECHNICAL FIELD

The present technology is directed generally to a blade design for usein a wind turbine, wind turbines implementing the blade design (such asa plurality of the blades), and a wind turbine generator assemblyimplementing a wind turbine.

BACKGROUND

Current developments in wind turbine design often focus on large scalekilowatt and megawatt installations. In such cases, fewer, very-largeblades have been found to be most efficient. For example, adding morethan 3 blades to very large turbines has been reported to producediminishing returns in energy production. Additionally, more blades onvery large scale turbines results in a much noisier turbine due in partto the aerodynamic effects of air flowing over the blade surfaces.Moreover, large commercial turbine power generating systems need to belocated in specific high-wind locations, such as the crests of hills inwindy geographies.

Smaller scale applications, such as those related to domestic, marine,and remote field power generation, have different requirements. Forexample, domestic or mobile turbines, by their nature, may be placed inlocations with inconsistent or low winds.

Current turbines of any size produce undesirable levels of noise, atleast in part because of aerodynamic effects of current blade designschopping the air (a constant whooshing sound). Accordingly, in someinstances, users may lock such turbines and avoid their use when peopleare nearby, such as when a boat is occupied or when people nearby aresleeping. If a user chooses to lock a turbine at night to reduce noise,the undesirable noise has the ultimate effect of reducing the turbine'sefficacy. Such undesirable noise levels may also contribute to therelatively higher popularity of solar energy for domestic, home-based,and/or off-grid power generation, despite the fact that solar power doesnot work at night, while wind power does. And current turbines are lessportable than solar panels or batteries, so solar power and batteriesare a predominant power source for remote uses by hikers or others inremote areas.

Accordingly, there is a need for quieter turbines, turbines that cangenerate power at low wind speeds, turbines with improved efficiency,and—for many applications—turbines and related assemblies for powergeneration that are light weight, resilient, and/or portable.

Such small-scale and/or local turbines can be referred to as distributedwind energy. Distributed wind energy is local wind energy productionimplemented near the site of energy use, as opposed to large-scale windenergy production like the wind farms operated by utility companies.Examples of distributed wind may include the above domestic, marine,and/or remote implementations. Distributed wind can be implemented tosupport off-grid sites or it can supplement on-grid sites.

The United States Department of Energy has recognized that distributedwind energy is not only feasible; it has the potential to become a majorsource of energy during the next several decades. But to become such amajor source of energy, distributed wind devices need to be lower incost, more efficient, and easier for consumers to implement.

Many shapes in nature have evolved over millions of years to provideefficient solutions to survival problems for natural organisms.Biomimicry in some manmade devices has taken advantage of conceptslearned from analysis of natural biological solutions. One importantmechanism is the fin of a humpback whale, which has structures calledtubercles that scientists have credited with improved maneuverabilityand efficiency for the whale due to improved fluid dynamics.

SUMMARY

The following summary is provided for the convenience of the reader andidentifies several representative embodiments of the disclosedtechnology. Such representative embodiments are examples only and do notconstitute the full scope of the invention.

Representative embodiments of the present technology include a windturbine generator assembly for converting wind into electrical energy.The assembly can include a wind turbine and a generator configured toreceive rotational force from the wind turbine and convert therotational force to electrical energy. The wind turbine can include amounting element and a plurality of turbine blades attached to themounting element. At least one of the turbine blades can include a root,a tip positioned opposite the root, and a leading edge spanning betweenthe root and the tip along a length of the blade. The leading edge canhave a length greater than a length of the root and a length of the tip.The at least one of the turbine blades can include a trailing edgepositioned opposite the leading edge and spanning between the root andthe tip along the length of the blade. The root can include a pluralityof curved projections.

In some embodiments, the at least one of the turbine blades can have aradius of curvature along its length forming a concave face orientedaway from the mounting element. The root and the tip can be rotated ortwisted relative to each other such that the at least one of the turbineblades is twisted along its length. The mounting element can include amounting plate having a central region and a plurality of arms extendingoutwardly from the central region. Each turbine blade can be supportedby at least one of the plurality of arms. The wind turbine generatorassembly can include a mounting flange configured to connect themounting element to the generator. The at least one of the turbineblades can include high density polyethylene (HDPE).

In another representative embodiment of the present technology, a windturbine can include a mounting element and a plurality of turbineblades. Each turbine blade can include a curved root positioned adjacentthe mounting element, a tip positioned opposite the root, a leading edgespanning between the root and the tip along a length of the turbineblade, and a trailing edge spanning between the root and the tipopposite the leading edge. Each turbine blade can have a radius ofcurvature along its length to form a concave face oriented away from themounting element. The root and the tip of each turbine blade can berotated relative to each other such that each turbine blade is twistedalong its length. Each turbine blade can be attached to the mountingelement closer to the trailing edge of the turbine blade than to theleading edge of the turbine blade such that an intersection of theleading edge of each turbine blade and the root of each turbine bladeprojects upstream from the wind turbine. The root can include aplurality of tubercles distributed along the curvature of the root.

In some embodiments, each turbine blade of the plurality of turbineblades at least partially overlaps another turbine blade of theplurality of turbine blades. Each turbine blade can include high densitypolyethylene (HDPE). Each turbine blade can include one or more additivematerials configured to inhibit UV radiation, stiffen the turbine blade,reduce brittleness, and/or color the turbine blade. In some embodiments,the wind turbine can include a mounting flange configured to connect themounting element to a shaft of a generator. The root and the tip of aturbine blade can be rotated relative to each other by a washout angleof between 16 and 20 degrees. Each turbine blade can be attached to themounting element via a generally flat region of the turbine blade.

In another representative embodiment of the present technology, a bladefor a wind turbine can include an elongated and curved sheet having acurved root, a curved tip positioned opposite the root, a leading edgespanning between the root and the tip along a length of the blade, and atrailing edge spanning between the root and the tip opposite the leadingedge. The root and the tip can be rotated relative to each other suchthat the blade is twisted along its length. The root can include an edgehaving a plurality of curved projections, the curved projections beingdistributed along a curvature of the root.

In some embodiments, a region of the blade adjacent the trailing edgecan be generally flat. The blade can include one or more mounting holesconfigured to connect the blade to a mounting element. The blade caninclude high density polyethylene (HDPE). The root and the tip can berotated relative to each other by a washout angle of between 16 and 20degrees.

In another representative embodiment of the present technology, a windturbine system can include a mounting element and a plurality of turbineblades, each turbine blade including an elongated and curved sheet witha first edge, a second edge positioned opposite the first edge, and agenerally concave surface between the first edge and the second edge.The concave surface is oriented to face a generally upstream direction.Each turbine blade can include one or more air dams. The air dams can bein the form of strip elements spanning at least a portion of a distancebetween the first edge and the second edge and extending upstream andaway from the concave surface. In some embodiments, each turbine bladehas a third edge connecting the first edge to the second edge, and afourth edge positioned opposite the third edge. At least one of thestrip elements can be positioned at a distance from the third edge andthe fourth edge. In some embodiments, the one or more strip elements caninclude two or more strip elements. In some embodiments, the third edgecan include a plurality of projections extending toward projections ofanother turbine blade, and the projections can be distributed betweenthe first edge and the second edge along a length of the third edge. Insome embodiments, at least one of the first edge and the second edge canbe a leading edge and the third edge can be a root. In some embodiments,the wind turbine system can further include a generator configured to beconnected to the mounting element to convert movement of the turbineblades to electrical energy.

In another representative embodiment of the present technology, a bladefor a wind turbine can include a root, a tip positioned opposite theroot, a leading edge spanning between the root and the tip along alength of the blade, and a trailing edge spanning between the root andthe tip opposite the leading edge. The blade can include a generallyconcave surface formed by a curvature of the blade about a longitudinalaxis of the blade. The blade can further include one or more stripelements oriented transverse to the longitudinal axis and extending awayfrom the concave surface. In some embodiments, the root includes a rootedge connecting the leading edge to the trailing edge. A plurality ofcurved projections can be distributed along the root edge. In a furtherrepresentative embodiment of the present technology, a wind turbine caninclude a mounting element and a plurality of turbine blades.

Other features and advantages will appear hereinafter. The featuresdescribed above may be used separately or together, or in variouscombinations of one or more of them.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein the same reference number indicates the sameelement throughout the views:

FIG. 1 illustrates a view of a turbine blade employing tubercles inaccordance with an embodiment of the present technology.

FIG. 1A illustrates a generally edge-on view of the turbine blade shownin FIG. 1.

FIG. 1B illustrates a schematic view of the root of a turbine bladeemploying tubercles in accordance with an embodiment of the presenttechnology.

FIG. 2A is a partially schematic line or wire diagram to illustrate someof the curvature of the turbine blade shown in FIG. 1.

FIG. 2B is a partially schematic shaded view of the turbine blade shownin FIG. 1, with the same perspective as in FIG. 2A.

FIG. 3 illustrates an end view of a turbine blade, with a root in theforeground, extending to a tip in the background, in accordance with anembodiment of the present technology.

FIG. 4 illustrates a view of a turbine blade in accordance with anotherembodiment of the present technology.

FIG. 4A illustrates an isometric view of a turbine blade with an air damin the form of a strip element in accordance with another embodiment ofthe present technology.

FIG. 4B illustrates an approximate root end view of the turbine bladeshown in FIG. 4A.

FIG. 4C illustrates an isometric view of a turbine blade with an air damin the form of a strip element in accordance with another embodiment ofthe present technology.

FIG. 4D illustrates an approximate root end view of the turbine bladeshown in FIG. 4C.

FIG. 5 illustrates a rear view of a turbine constructed using theturbine blades shown in FIGS. 1-4D in accordance with an embodiment ofthe present technology, in which the turbine blades and a mounting plateare visible.

FIG. 6 illustrates a front view of the turbine shown in FIG. 5.

FIG. 7 illustrates a side view of a turbine (such as a turbine shown inFIGS. 5-6), in which the turbine is attached to a generator drive shaftvia a mounting flange.

DETAILED DESCRIPTION

The present technology is directed to a wind turbine blade, a windturbine, and associated systems and methods. Various embodiments of thetechnology will now be described. The following description providesspecific details for a thorough understanding and an enablingdescription of these embodiments. One skilled in the art willunderstand, however, that the invention may be practiced without many ofthese details. Additionally, some well-known structures or functions maynot be shown or described in detail so as to avoid unnecessarilyobscuring the relevant description of the various embodiments.Accordingly, the technology may include other embodiments withadditional elements or without several of the elements described belowwith reference to FIGS. 1-7, which illustrate examples of thetechnology.

The terminology used in the description presented below is intended tobe interpreted in its broadest reasonable manner, even though it isbeing used in conjunction with a detailed description of certainspecific embodiments of the technology. Certain terms may even beemphasized below; however, any terminology intended to be interpreted inany restricted manner will be overtly and specifically defined as suchin this detailed description section.

Where the context permits, singular or plural terms may also include theplural or singular term, respectively. Moreover, unless the word “or” isexpressly limited to mean only a single item exclusive from the otheritems in a list of two or more items, then the use of “or” in such alist is to be interpreted as including (a) any single item in the list,(b) all of the items in the list, or (c) any combination of items in thelist. Further, unless otherwise specified, terms such as “attached” or“connected” are intended to include integral connections, as well asconnections between physically separate components.

Specific details of several embodiments of the present technology aredescribed herein with reference to wind turbines. The technology mayalso be used in other areas or industries in which fluid flow is used togenerate electricity and/or to rotate a turbine for other applications,including, for example, flow of a liquid. Conventional aspects of someelements of the technology may be described in reduced detail herein forefficiency and to avoid obscuring the present disclosure of thetechnology.

Wind Turbine Blades

The present technology includes turbine blades that provide improvedefficiency and high torque relative to their size.

As will be described in additional detail below, a turbine blade inaccordance with an embodiment of the present technology may be formedfrom a curved sheet (such as a curved elongated quadrilateral sheet)which is also twisted and includes ridges or tubercles on a root or rootedge for improved efficiency. In a representative embodiment, a blademay have between 16 and 20 degrees of twist (such as 18 degrees oftwist), regardless of the overall size or length of the blade or otherdimensions. The twist of a blade may be referred to as “washout.” It canalso be understood in part as the root and the tip of a blade beingrotated or twisted relative to each other. The shape of each blade isdesigned to maintain even pressure distribution along the whole face ofthe blade. Such even pressure distribution and resistance to blade tipstall condition improves performance and reduces wind noise.

Turning now to the figures, FIG. 1 illustrates a view of a turbine blade101 employing ridges, protuberances, or tubercles 111 in accordance withembodiments of the present technology. The blade can be generally shapedas a quadrilateral or elongated quadrilateral sheet with a root 102 onone side and a tip 103 opposite the root 102. A trailing edge 105, whichmay be straight in some embodiments (or curved in others), spans adistance or length 109 between the root 102 and the tip 103. A leadingedge 104, which may be curved in some embodiments (or straight inothers), is positioned opposite the trailing edge 105 and spans betweenthe root 102 and the tip 103. A width 107 of the root 102 can be largerthan a width 108 of the tip 103. For example, in a representativeembodiment, the width 107 of the root 102 is approximately twice thewidth 108 of the tip 103. In other embodiments, the width 107 of theroot 102 can have other suitable sizes relative to the width 108 of thetip 103.

One or more mounting holes 106 can be located along the trailing edge105 near the root 102, or they may be positioned in other suitablelocations for mounting the turbine blade 101 to a mounting element (suchas a hub or other structure, as described in additional detail below).For example, the mounting holes 106 can have a diameter of 0.25 inchesor another suitable diameter. The mounting holes 106 can be positionedat a distance of 0.5 to 0.6 inches (such as 0.5 inches) from thetrailing edge 105. In an embodiment having two mounting holes, they canbe spaced apart by 4.625 inches, or by any other suitable distance. Theymay be positioned a suitable distance away from the root 102. A region110 of the blade 101 near and/or surrounding the mounting holes 106 canbe flat in some embodiments to improve mounting and to help the blades101 to have a suitable angle of attack against the incoming wind. Forexample, each blade 101 can be attached to the mounting element closerto the trailing edge 105 than to the leading edge 104 such that anintersection or intersection region 112 of the leading edge 104 and theroot 102 of each blade 101 projects upstream from a mounting element ofa wind turbine employing the blade 101 (see FIG. 7).

A turbine blade 101 in accordance with embodiments of the presenttechnology can have a length 109 of approximately 15 inches toapproximately 36 inches, or larger or smaller lengths depending onapplication and power generation needs. For example, in representativeembodiments, a turbine blade 101 can have a length of 24.6 inches, 32.5inches, or other suitable lengths such as 5 feet or more. For a bladehaving a length 109 of 24.6 inches, the root 102 can have a width 107 ofapproximately 6.2 inches and the tip 103 can have a width 108 ofapproximately 4.7 inches. In further embodiments, the blade 101 can havea width 107 at the root 102 of approximately 8.5 inches, and a width 108at the tip 103 of approximately 3.25 inches. For a blade having a length109 of 32.5 inches, the root 102 can have a width 107 betweenapproximately 8.0 and 8.6 inches (such as 8.56 inches) and the tip 103can have a width 108 of approximately 3.25 inches. A turbine blade 101in accordance with various embodiments can have other suitabledimensions. For example, a ratio of the length 109 of the trailing edge105 to the width 107 of the root 102 to the width 108 of the tip 103 canbe approximately 8:2:1. In a blade having a length of 32.5 inches, aradius of curvature of the leading edge 104 can be approximately 10feet, or other suitable dimensions. Edges of the blade 101 can bechamfered or rounded to reduce drag, reduce weight, and/or for otherreasons. For example, the leading edge 104, the trailing edge 105,and/or other edges can be chamfered or rounded. FIG. 1A illustrates agenerally edge-on view of the turbine blade 101 shown in FIG. 1.

The inventors discovered that adding ridges or tubercles 111 to an edge,such as the edge at the root 102, improves efficiency. For example, in awind turbine assembly such as embodiments of the technology describedbelow, the root 102 functions like a leading edge cutting throughairflow and guiding the airflow to wash out along the blade 101 from theroot 102 to the tip 103. The tubercles 111 reduce flow separation (e.g.,they delay boundary layer separation) along the blade 101, improving thetransformation of wind force into rotational force for energygeneration. The tubercles also increase the angle of attack at whichstalling occurs, widening the airflow speed range in which the blades101 are effective. The inventors discovered that the tubercles providedthe most benefit along the edge at the root 102, as opposed to otherregions of the blade 101. Testing revealed that blades 101 withtubercles 111 at the root 102 provide as much as 10 percent additionalefficiency relative to blades without tubercles 111 in a typicalwindspeed range of 0 to 25 miles per hour. Such an increase inefficiency, combined with the efficiency provided by use of HDPEmaterial in terms of cost and mechanical efficiency (described below),increase the feasibility of distributed wind systems. Although thetubercles 111 are described as such, the tubercles 111 may also bedescribed as curved projections extending from, or forming part of, theroot 102.

FIG. 1B illustrates a schematic view of a representative root endportion of the blade 101 (the root 102 is shown, along with a portion ofthe blade 101 adjacent to the root 102; the remainder of the blade 101is omitted) having tubercles 111 in accordance with an embodiment of thepresent technology. FIG. 1B is a viewpoint from an upwind perspective.The inventors discovered that one efficient tubercle arrangement can bedefined by, on one hand, amplitude of curvature, and on the other hand,distance along the curve of the root 102 from the trailing edge 105. Forexample, in a 32.5 inch blade, one tubercle 111 can be shaped to have anamplitude A1 of 1.2 inches, with a distance D1 between the trailing edge105 and a maximum peak of the tubercle being approximately 0.7 inches.Moving from the trailing edge 105 toward the leading edge 104, anothertubercle 111 can be shaped to have an amplitude A2 of 0.2 inches, with adistance D2 between the trailing edge 105 and a maximum peak of thetubercle being approximately 4.2 inches. Another tubercle 111 can beshaped to have an amplitude A3 of 0.2 inches, with a distance D3 betweenthe trailing edge 105 and a maximum peak of the tubercle beingapproximately 6.0 inches. Another tubercle 111 can be shaped to have anamplitude A4 of 0.6 inches, with a distance D4 between the trailing edge105 and a maximum peak of the tubercle being approximately 8.0 inches.Another tubercle 111 can be shaped to have an amplitude A5 of 0.7inches, with a distance D5 between the trailing edge 105 and a maximumpeak of the tubercle being approximately 10.1 inches. Note that thedistances D1-D5 are distances along the arc or curvature of the root 102(the curvature is visible, for example, in FIGS. 2A and 2B, describedbelow).

In other embodiments, other suitable dimensions can be used. Forexample, the foregoing dimensions can be scaled up or down depending onthe size of the blade 101, or the dimensions may be kept constant. Notethat for purposes of illustration, the dimensions D1, D2, D3, D4, and D5are provided as distances along the arc of the root 102. In someembodiments, the number of tubercles 111 may be between 9 and 11, whilein a particular embodiment, as illustrated, there may be approximately 5tubercles. In other embodiments, other numbers of tubercles may be used.

FIGS. 2A and 2B illustrate additional views of the turbine blade 101shown in FIG. 1. FIG. 2A is a partially schematic line or wire diagramto illustrate some of the curvature of the turbine blade 101 shown inFIG. 1. FIG. 2B is a partially schematic shaded view of the turbineblade 101 shown in FIG. 1, with the same perspective as in FIG. 2A. Ineach of FIGS. 2A and 2B, as described above, the turbine blade 101 has aroot 102, a tip 103 opposite the root 102, a leading edge 104 spanningbetween the root 102 and the tip 103, and a trailing edge 105 spanningbetween the root 102 and the tip 103. The mounting holes 106 arepositioned along the trailing edge 105 and near the root 102. Lines 201are provided to illustrate the curvature of the turbine blade 101 abouta long or longitudinal axis (e.g., along or aligned with the length 109shown in FIG. 1) running from the root 102 to the tip 103. For example,the blade 101 can be curved about an axis extending from the root 102 tothe tip 103 between the leading edge 104 and the trailing edge 105. Inother words, the radius of curvature is generally oblique to the lengthof the blade 101 or transverse to the length of the blade 101 (such asperpendicular). In a representative embodiment, such as in a 32.5 inchblade, a radius of curvature of the lines 201 can be about 7 inches, orit can have other suitable dimensions. In a representative embodiment,the turbine blade 101 can have a parabolic shape and a curvature at anapex of a parabola or centerline of the blade can be 7 inches. In someembodiments, the radius of curvature need not be uniform along thelength 109 from the root 102 to the tip 103. In a further representativeembodiment, the turbine blade 101 is twisted (“washout”) about an axisrunning the length of the turbine blade 101, such as a centerline, by 18degrees, as further illustrated in FIG. 3. Such a compound curveprovides structural integrity while distributing even wind pressureacross the face of the blade 101. The tubercles 111 further improveefficiency relative to blades without such tubercles, as describedabove.

FIG. 3 generally illustrates an end view of the turbine blade 101 shownin FIGS. 1, 1A, 2A, and 2B, with the root 102 in the foreground,extending to the tip 103 in the background. Note that tubercles (forexample, tubercles 111 described above) are not shown in FIG. 3 forsimplicity of illustration. A curvature 304 of the root 102 is depictedas a dashed line (304). A curvature 305 of the tip 103 is also depictedas a dashed line (305). In a representative embodiment (such as a bladehaving a length of 32.5 inches), the radius of the curvature 304 of theroot 102 and the radius of the curvature 305 of the tip 103 isapproximately 7 inches. In other embodiments, the radius of thecurvatures 304 and 305 may be different, or the 7-inch curvature can beused with other lengths of blades. For example, the radius of curvature305 of the tip 103 and/or the radius of curvature 304 of the root 102may be between approximately 3 inches and 7 inches on blades of variouslengths. The blade 101 can have a thickness T in the range of 3millimeters to 6 millimeters, for example, or it may have anothersuitable thickness. The thickness T can be uniform across the blade 101or it can vary in different regions of the blade 101.

The inventors discovered that uniform thickness (for example, 0.174inches when using HDPE material described below) provides optimalefficiency and performance. Uniform thickness can be achieved usinginjection molding, for example. The thickness of the blades can becontrolled using injection molding so that, for example, longer bladesmay have increased thickness relative to shorter blades. When the bladehas generally uniform thickness, several benefits are realized. Forexample, manufacturing is simplified. When the material thickness isuniform, the material heats and cools at approximately the same rate,which resists or prevents warping. In some embodiments, however, theblade thickness T can vary (e.g., it may be tapered from the root 102 tothe tip 103). In some embodiments, the thickness T can vary such thatthe blade is thickest in the area closest to the mounting holes 106 andit becomes progressively thinner from there toward the other edges andother regions of the blade.

In a representative embodiment, the turbine blade 101 has a parabolicshape. For example, the curvature 304 and/or 305 may be parabolic. Insuch embodiments, the radius of curvatures 304 and/or 305 can bemeasured at a center point or vertex of such a parabolic shape, at acentral point along the root 102 or the tip 103.

FIG. 3 also illustrates the twist, or washout, of the blade 101. Thetwist can be measured by an angle 312 between a first line 310 and asecond line 311, which can be explained as follows. A first center point306 of the root 102 is positioned between the leading and trailing edges104, 105. A first tangent line 308 is tangent to the curvature 304 ofthe root 102 at the first center point 306. The first line 310 isperpendicular to the first tangent line 308 at the first center point306. Similarly, a second center point 307 of the tip 103 is positionedbetween the leading and trailing edges 104, 105. A second tangent line309 is tangent to the curvature 305 of the tip 103 at the second centerpoint 307. The second line 311 is perpendicular to the second tangentline 309 at the second center point 307. The first line 310 and thefirst tangent line 308 define a first plane. The second line 311 and thesecond tangent line 309 define a second plane parallel to the firstplane. The angle 312 is the angle between the first line 310 projectedonto the second plane (defined by the second line 311 and the secondtangent line 309) and the second line 311. The angle 312, representingthe twist or “washout” can be between 16 and 20 degrees in someembodiments.

In a representative embodiment of the present technology, the angle 312can be 18 degrees. The 18-degree washout resists (e.g., prevents)negative blade tip stall condition and keeps positive wind pressure onthe correct side of the tips at the widest range of wind speeds.Computational fluid dynamics analysis and wind tunnel testing revealedthat the 18-degree washout angle yields approximately 9% more energyrelative to a blade having a 16-degree washout angle. Accordingly, thegeometry of the blade 101 contributes to performance of a turbine usingthe blade 101, especially with regard to improved efficiency.

In various embodiments according to the present technology, the twist(i.e. washout or angle 312) is 18 degrees regardless of the length(e.g., length 109, see FIG. 1) of the blade 101. For example, whenembodiments of the present technology are scaled up or down (such asrelative to a representative length of 32.5 inches) while maintainingwashout of 18 degrees, the additional length of a blade 101 does notmerely become excess weight and/or surface area for drag. Rather,generally the entire face of the blade contributes substantially toproviding torque for a turbine assembly of suitable sizes larger andsmaller than those disclosed herein.

A blade 101 or a plurality of blades 101 according to the presenttechnology maintain even pressure distribution along the whole face ofthe blade as it receives an incoming airstream or wind. Benefits to suchgeometric designs and pressure distribution include higher performance,increased efficiency, and reduced noise (e.g., silent or almost silent)relative to conventional turbines and/or turbine blades.

In some embodiments, a blade 101 is made of lightweight polymericmaterial and is especially shaped to accommodate the use of suchmaterial. In a representative embodiment, the blade 101 is made from athermoplastic such as high density polyethylene (HDPE). In someembodiments, the shape of the blade 101 accommodates such a flexiblematerial to provide the stiffness required of a wind turbine blade. Forexample, under extremely high wind conditions, a turbine can be designedto flip (i.e. rotate around to face away from the wind) and the bladewill flex to avoid destruction of the turbine. In other words, undernormal operation, wind pushing on the front of a blade 101 will inducetorque in the blade 101, which is generally stiff in that direction as aresult of its curvature. But when the blade 101 receives pressure on itsreverse side (the side not normally facing into the wind), it can flex,without breaking, and return to shape after the wind has diminished.Further, the flexibility of HDPE helps manage overspeed or over-revvingin storms or extremely high wind conditions by slightly pitching intothe wind and reducing the angle of attack (and thereby reducing thetorque and speed to keep them within safe levels). In a representativeembodiment of the present technology, high molecular weight HDPE can beused to form the blade (for example, hexene copolymer HDPE blow moldingresin). Advantages of HDPE include properties resistant to extremetemperature change and flexibility with reduced risk of fracture, aswell as relatively low cost compared to metals or composites.

In some embodiments, the material used to make the blade 101 (such asHDPE) can include one or more additives for protection from ultraviolet(UV) radiation (such as a UV inhibitor), one or more additives to reducebrittleness, one or more additives to modify the color of the finishedblade 101, one or more additives to improve stiffness (such as nylon),and/or other additives suitable for providing desired aesthetic and/orfunctional qualities.

In other embodiments, the blade is made from a fiber reinforced plastic(which may be HDPE or another plastic material). One non-limitingexample of such a material is a composite employing carbon fibers and/orglass fibers in an epoxy base. Such composites have demonstratedexceptional strength and durability combined with light weight fordemanding applications in the automotive, medical and industrialindustries. Additionally, these composites are relatively easy to forminto precise, complex shapes without the need for precision stamping ormilling operations. Another non-limiting example of a fiberreinforcement material may include nylon fibers.

In yet further embodiments, other suitable materials may be used to formall or a part of the blade 101, such as PVC (polyvinyl chloride), ABS(acrylonitrile butadiene styrene), silicone, fiberglass, wood, compositestructures formed from wood or other suitable layers, and/or varioustypes of polymers or plastics, such as polypropylene. However, highmolecular weight HDPE functions best in terms of flexibility, resistanceto failure, and maintaining properties across a wide temperature range.

FIG. 4 illustrates a view of a turbine blade 401 in accordance withanother embodiment of the present technology. The turbine blade 401 maybe generally similar to the turbine blade 101 described above withregard to FIGS. 1-3, having a root 402, a tip 403, and a trailing edge405, for example. The turbine blade 401 can have a length 409 betweenthe root 402 and the tip 403 of 24.4 inches. The turbine blade 401 caninclude tubercles 111 similar to those described above with regard toFIGS. 1-2B, for improved efficiency.

FIGS. 4A and 4B illustrate a turbine blade 450 in accordance withanother embodiment of the present technology. FIG. 4A illustrates anisometric view of the turbine blade 450 and FIG. 4B illustrates anapproximate root end view of the turbine blade 450. With regard to bothFIGS. 4A and 4B, the turbine blade 450 can be generally similar to theturbine blade 101 described above with regard to FIGS. 1-3, with a root452, a tip 453, a leading edge 454, and a trailing edge 455, forexample. The turbine blade 450 can optionally include tubercles 111similar to those described above with regard to FIGS. 1-2B, for improvedefficiency. In addition, the turbine blade 450 can include one or moreair dams 460 projecting upstream from the concave face or concavesurface 465 of the turbine blade 450. In some embodiments, one or moreof the air dams 460 can be in the form of a strip element as illustratedin FIGS. 4A-4D and as described in additional detail below. One such airdam 460 (in the form of a strip element) is illustrated in FIGS. 4A and4B, but any suitable number of air dams 460 can be used.

An air dam according to embodiments of the present technology can be inthe form of a rigid, semi-rigid, or flexible strip element extendingupwind and away from the concave face 465 of the turbine blade 450 andspanning between the leading and trailing edges of the turbine blade450. In some embodiments, one or more air dams (such as air dams in theform of strip elements) can only span the partial distance between theleading and trailing edges of the turbine blade, while in otherembodiments, one or more air dams can span the full distance between theleading and trailing edges. In some embodiments, air dams can be flat orgenerally flat along their surface, contoured between their edges, orotherwise shaped. In some embodiments, one or more air dams can beperpendicular to the concave face 465, while in other embodiments, oneor more air dams can be oriented at an oblique angle relative to theconcave face 465. In some embodiments, one or more air dams can beoriented generally perpendicular to a longitudinal axis of a turbineblade 450 (in other words, generally perpendicular to length L1), whilein other embodiments, one or more air dams can be oriented at an obliqueor other angle relative to the longitudinal axis of the turbine blade450. In some embodiments, one or more air dams can be formed with thesame material as the blade 450, and in further embodiments, the air damscan optionally be formed at the same time as (such as co-molded with)the blade 450. In other embodiments, air dams can be made from differentmaterials than the blade 450 and mounted to the blade 450 usingadhesive, fasteners, or another suitable means of attachment.

In some embodiments, one or more air dams 460 can have the same materialthickness as the material thickness of the turbine blade 450. In otherembodiments, one or more air dams 460 can be approximately 30% thinnerthan the turbine blade 450, for example, to reduce weight.

In operation, each air dam 460 provides resistance to the air washingout along the concave face 465 of the turbine blade 450 from the root452 to the tip 453. The air dam 460 therefore increases the torquedelivered by rotational motion of a turbine having the blade 450.Accordingly, positioning one or more air dams 460 along the length L1 ofthe turbine blade 450 improves efficiency.

Although FIGS. 4A and 4B illustrate a turbine blade 450 having both (a)tubercles 111 and (b) an air dam 460, some blades according toembodiments of the present technology can omit the tubercles 111. Insuch blades without tubercles 111, the root 452 can have any suitablyshaped edge (for example, flat, curved, or other suitable edge shape).Accordingly, one or more air dams 460 can be implemented in the blade450 with or without tubercles 111.

In a particular representative embodiment of the present technology, inwhich a length L1 of the turbine blade 450 is between 35 and 37 inches(for example, 36 inches), an air dam 460 can be positioned at a distanceL2 between 11 and 12 inches from the edge of the root 452 (for example,11.5 inches). An air dam 460 according to various embodiments of thepresent technology can be a strip element extending from the concaveface 465 of the turbine blade 450, and a forward-facing upstream edge470 can, but need not be, flush with the leading edge 454 and with thetrailing edge 455. In some embodiments, the air dam 460 can extend fromthe concave face 465 to the upstream edge 470 along a distance L3between 1 and 2 inches (for example, 1.5 inches).

FIGS. 4C and 4D illustrate a turbine blade 480 in accordance withanother embodiment of the present technology. FIG. 4C illustrates anisometric view of the turbine blade 480 and FIG. 4D illustrates anapproximate root end view of the turbine blade 480. In some embodiments,the turbine blade 480 can be generally similar to the turbine blade 450described above with regard to FIGS. 4A and 4B. In a particularrepresentative embodiment, the turbine blade 480 can have an air dam 482positioned near the tip 453 of the turbine blade 480. For example, in aturbine blade 480 having an overall length L4 of approximately 36inches, an air dam 482 can be positioned at a distance L5 ofapproximately 35 inches from the edge of the root 452 (or approximatelyone inch from the edge of the tip 453). In some embodiments, an air dam482 can be positioned at the edge of the tip 453, such that it is flushwith the tip 453.

An air dam 482 according to various embodiments of the presenttechnology can be a strip element extending from the concave face 465 ofthe turbine blade 480, and a forward-facing upstream edge 485 of the airdam 482 can, but need not be, flush with the leading edge 454 and withthe trailing edge 455. In some embodiments, the air dam 482 can extendfrom the concave face 465 to the upstream edge 485 along a distance L6of approximately 0.25 inches. In some embodiments, air dams can extendbeyond a line between the leading and trailing edges 454, 455. Forexample, the air dam 482 can be taller than or stick out past one orboth of the leading and trailing edges 454, 455. In some embodiments,the distance L6 can be a value of up to 50 percent of the width of thetip 453 (between the leading and trailing edges 454, 455.

In some embodiments, the position of an air dam along the length of ablade may determine the distance L6 (or L3 in FIG. 4B) because the depthof the curvature of the surface of the concave face 465 may vary alongthe length of the blade.

Although specific dimensions have been provided in the context ofseveral embodiments of the present technology, various lengths of bladesand various quantities and positions of air dams (such as air dams 460,482) are contemplated within the various embodiments. For example,dimensions provided herein can be scaled up or down. Any desired numberof air dams can be used in various embodiments. Air dams in variousembodiments need not be flush with a leading or trailing edge or withother edges.

Turbine Including Mounted Array of Blades

The present technology also includes a turbine made with a mounted arrayof turbine blades, such as the turbine blades 101, 401, 450, or 480described above with respect to FIGS. 1-4D.

FIG. 5 illustrates a partially schematic rear view of a turbine 700, inwhich a plurality of turbine blades 101 (alternatively, other turbineblades according to various embodiments of the present technology) aremounted to a mounting plate 701 via mounting holes 406 of the mountingplate 701. Such a view is looking upstream and at the convex sides ofthe blades 101. The rear side of the mounting plate 701 can include arecess 600 to receive a drive shaft associated with a generator,described in further detail below. For illustration, the leading edge104 and the trailing edge 105 of one of the blades 101 are indicated.Although 9 blades 101 are illustrated, any suitable number of blades canbe used in accordance with various embodiments of the presenttechnology.

The mounting plate 701 is a generally flat star- or circular-shapedplate including a flat circular central region 704 and one or moretapered arms 702 (for example, 9 tapered arms 702 or a suitable numberof tapered arms to correspond with the number of blades 101). Thetapered arms 702 radiate outwardly from the central region 704. The armsare arranged symmetrically about the central region 704 withcorresponding rounded or curved tips 703 of the arms (at the end of eacharm 702) being narrower than the base portion or attachment pointconnecting the arm 702 to the central region 704. The rounded tips 703provide improved efficiency relative to non-rounded tips due to thecorresponding reduction in material and weight. The arms need not betapered in some embodiments. Note that for the purposes of illustration,not every element is labeled in FIG. 5. The reader will understand thatthe mounting plate 701 is symmetric and elements are repeated around themounting plate 701 several times. The mounting plate 701 can have anoverall width between 15 inches and 18 inches (for example, it may besized such that an imaginary circle contacting each of the tips 703 hasa diameter between 15 inches and 18 inches), or it can have othersuitable dimensions.

Each arm 702 includes a first edge 503 and a second edge 504 oppositethe first edge 503. The mounting holes 406 are positioned near the firstedge 503. The mounting holes 406 are positioned to align withcorresponding mounting holes on the turbine blades described above (forexample, mounting holes 106 in the turbine blades described above orillustrated with respect to FIGS. 1-4D). When the mounting holes on theturbine blades are mated with the mounting holes 406 on the mountingplate 701, the trailing edge of each turbine blade (for example, thetrailing edge 105 of the turbine blade 101 described above with respectto FIGS. 1-3) aligns with the first edge 503 of the mounting plate 701.Bolts with nuts can be used to mount, clamp, or connect the turbineblades 101 to the mounting plate 701. Other suitable fasteners, such asrivets, pins, or clips, can additionally or alternatively be used tomount the turbine blades 101 to the mounting plate 701. Once connected,the location of the mounting holes 406 results in a stiffening of theblades 101 along the trailing edge 105.

In various embodiments, the mounting plate 701 is formed from a stiffmaterial such as steel or plastic. In other embodiments, the mountingplate 701 can be formed from a variety or combination of materialssuitable to support turbine blades and carry loads to transfer torque toa generator. For example, the mounting plate 701 can be formed fromsteel with a thickness between 3/16 of an inch and 0.5 inches, or othersuitable dimensions depending on material, implementation, and bladesize. In a representative embodiment, the mounting plate 701 is ⅜ of aninch thick. One or more bolts (not shown) pass through the turbineblades 101 and the mounting plate 701 to secure the turbine blades tothe mounting plate 701. In other embodiments, other suitable fastenerscan be used.

FIG. 6 generally illustrates a partially schematic front view of theturbine 700 (looking downstream). The tubercles 111 are visible at theroot 102 of each blade 101. Although air dams are not illustrated inFIG. 6, blades with air dams (such as blades 450, 480 with air dams 460,482) can be included in the turbine 700. Moreover, for blades with airdams, the tubercles 111 can optionally be omitted. When assembled into aturbine 700, the blades 101 can be spaced apart and symmetricallyoverlapping, such that a leading edge 104 of each blade overlaps itsneighboring blade 101. The symmetrical pattern also results in all thetips 103 of the blades 101 being equidistant apart and equidistant froma center of the turbine 700. The curvature of the blades 101 is suchthat the blade faces are concave in the view of FIG. 6. The convex sidesopposite the blade faces are positioned toward the mounting plate 701and downstream of normal wind during use (the concave faces resistbending backwards away from the wind during normal operation).

In some embodiments of the present technology, the mounting plate 701connects (directly or indirectly) to a generator or alternator to createelectricity from rotation due to the wind. For example, FIG. 7 generallyillustrates a side view of a turbine (such as a turbine 700 describedabove with respect to FIGS. 5-6), in which the turbine is attached to adrive shaft 800 via a mounting flange 801. The drive shaft 800 connectsto an alternator, generator, or other suitable device for convertingrotation to electrical energy. The flange 801 can limit or even preventbending or other damage to the mounting plate 701 and/or the drive shaft800 from the stress applied by incoming wind against the blades 101 byspreading the load applied to the mounting plate 701 and/or the driveshaft 800. The drive shaft 800 can have a diameter of approximately ¾inch, depending on implementation.

Wind Turbine and Generator Assembly

One representative advantage of blades 101 (or other embodiments ofturbine blades described herein, such as turbine blades 401, 450, 480)in accordance with the present technology is that they produce hightorque relative to their profile and size. Accordingly, blades andturbines (such as a turbine 700 described above with respect to FIGS.5-7) in accordance with the present technology can be used in manyremote or dedicated applications, such as cabins, camp sites, boats,remote environmental monitors, etc. Small wind turbines and electricgenerators powered by small wind turbines can be environmentally soundand economically attractive alternatives to conventional sources ofenergy. Representative blades and turbines in accordance with thepresent technology have improved efficiency for converting mechanicalenergy derived from the wind into electrical energy and they are able tooperate in both low wind and high wind conditions with reduced (e.g.,minimal) noise. Various wind turbines according to the presenttechnology can have an outer diameter of 24 inches to 80 inches, orother suitable dimensions, depending on application and need forportability.

In various embodiments, turbines, generators, and associated assembliesusing blades according to the present technology can be installed invarious locations, including permanent or semi-permanent locations, asdescribed in additional detail in U.S. patent application Ser. No.15/709,873 and in U.S. Pat. No. 9,797,370, each of which is incorporatedby reference herein in its entirety.

Wind turbine generator assemblies according to various embodiments ofthe present technology can include various suitable alternators orgenerators for converting rotational motion to electric energy. Forexample, in some embodiments, when a turbine according to the presenttechnology is connected to a suitable alternator or generator, the windturbine generator assembly may produce between 750 watts and 3kilowatts.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosed technology have been described for purposes ofillustration, but that various modifications may be made withoutdeviating from the technology, and elements of certain embodiments maybe interchanged with those of other embodiments. Embodiments of thepresent technology contemplate the use of any suitable number oftubercles. For example, in some embodiments, more tubercles may be usedin longer blades, while in other embodiments, fewer tubercles may beused in shorter blades. In yet other embodiments, the number oftubercles may be the same among various sizes of blades (for example,the tubercles may be scaled up or down in size corresponding to therelative blade sizes). Although tubercles and projections may bedescribed herein as being curved, in some embodiments, tuberclesaccording to the present technology may have one or more straight orgenerally straight portions and/or edges. Embodiments of the presenttechnology also contemplate the use of any suitable number of air damsin any suitable location. For example, in some embodiments, more airdams can be used on longer blades, while in other embodiments, fewer airdams can be used on shorter blades. In some embodiments, air dams can beused on blades without concave surfaces. Representative embodimentsdisclosed herein and illustrated in the accompanying figures showportions of assemblies and assemblies with a nine-blade turbinegenerator. In other embodiments, turbines can include any suitablenumber of blades and the mounting plates can include any suitablecorresponding number of arms (such as 7, 8, 10, 11, or 12 arms andblades). In some embodiments, dimensions may be scaled up or down whilemaintaining an 18-degree washout angle. In other embodiments, thewashout angle may be suitably modified.

Further, while advantages associated with certain embodiments of thedisclosed technology have been described in the context of thoseembodiments, other embodiments may also exhibit such advantages, and notall embodiments need necessarily exhibit such advantages to fall withinthe scope of the technology. Accordingly, the disclosure and associatedtechnology may encompass other embodiments not expressly shown ordescribed herein, and the invention is not limited except as by theappended claims.

What is claimed is:
 1. A wind turbine system comprising a mountingelement and a plurality of turbine blades, wherein at least one turbineblade of the plurality of turbine blades comprises: an elongated andcurved sheet having a first edge, a second edge positioned opposite thefirst edge, a third edge connecting the first edge to the second edge, afourth edge positioned opposite the third edge, a generally concavesurface between the first edge and the second edge, the concave surfacebeing oriented to face a generally upstream direction, and one or morestrip elements spanning at least a portion of a distance between thefirst edge and the second edge and extending upstream and away from theconcave surface, wherein at least one strip element is positioned awayfrom the third edge and the fourth edge.
 2. The wind turbine system ofclaim 1, wherein the one or more strip elements comprises two or morestrip elements.
 3. The wind turbine system of claim 1, wherein the thirdedge comprises a plurality of projections extending toward projectionsof at least one other turbine blade of the plurality of turbine blades,and the projections are distributed between the first edge and thesecond edge along a length of the third edge.
 4. The wind turbine systemof claim 1, wherein the first edge or the second edge is a leading edgeand wherein the third edge is a root.
 5. The wind turbine system ofclaim 1, wherein the turbine blade is attached to the mounting elementalong the first edge.
 6. The wind turbine system of claim 1, wherein thethird edge and the fourth edge are rotated relative to each other suchthat the turbine blade is twisted along its length.
 7. The wind turbinesystem of claim 1, wherein each turbine blade of the plurality ofturbine blades at least partially overlaps another turbine blade of theplurality of turbine blades.
 8. The wind turbine system of claim 1,further comprising a generator configured to be connected to themounting element to convert movement of the turbine blades to electricalenergy.
 9. A wind turbine comprising a mounting element and a pluralityof turbine blades, each turbine blade attached to the mounting element,each turbine blade comprising: a root; a tip positioned opposite theroot; a leading edge spanning between the root and the tip along alength of the turbine blade; a trailing edge spanning between the rootand the tip opposite the leading edge; a concave surface oriented awayfrom the mounting element; a convex surface positioned opposite theconcave surface and oriented toward the mounting element; and one ormore strip elements mounted to the concave surface and extending fromthe concave surface and spanning at least a portion of a distancebetween the first edge and the second edge, wherein the concave surfaceis located between the one or more strip elements and the convexsurface, and wherein at least one strip element is positioned away fromthe tip.
 10. The wind turbine of claim 9, wherein on at least oneturbine blade of the plurality of turbine blades, at least one of thestrip elements is positioned at a distance from the root.
 11. The windturbine of claim 9, wherein each turbine blade of the plurality ofturbine blades comprises a root edge and a plurality of projectionsdistributed along the root edge between the leading edge and thetrailing edge.
 12. The wind turbine of claim 9, wherein each turbineblade of the plurality of turbine blades at least partially overlapsanother turbine blade of the plurality of turbine blades.
 13. The windturbine of claim 9, wherein each turbine blade of the plurality ofturbine blades is attached to the mounting element closer to thetrailing edge of the turbine blade than to the leading edge of theturbine blade in a generally flat region of the turbine blade.
 14. Thewind turbine of claim 9, wherein for each turbine blade of the pluralityof turbine blades, the root and the tip are rotated relative to eachother such that each turbine blade is twisted along its length.